The present invention belongs to the technical field of a detecting material and method for judgement as to whether or not easily portable precision equipment for use in the open, such as cameras and mobile communication terminals, has undergone an improper usage condition, e.g., submersion in water or wetting with water, or whether or not articles of the type which are liable to suffer deterioration or have troubles when brought into contact with moisture or water, such as industrial products including precision equipment and drugs, clothing, foodstuffs, various kinds of records and cultural properties, have been in an inappropriate condition, specifically they have been placed under high humidity or have been gotten wet in rain, in the course of transportation or storage.
When electronic devices and precision equipment, inclusive of xe2x80x9ctake-alongxe2x80x9d cellular phones, which tend to have troubles by rain or water penetration of their interior, cause failures within the term of warranty on products by makers and need repairs, it becomes necessary to determine causes of the failures and judge whether or not the makers should assume responsibility for failures. On the other hand, it is also necessary to judge whether or not articles of the type which are liable to suffer deterioration or have troubles when brought into contact with moisture or water, such as industrial products including precision equipment and drugs, clothing, foodstuffs, various kinds of records and cultural properties, have been in an inappropriate condition, such as a high humidity condition or a condition of exposure to rain, in the course of transportation or storage, and distinguish between responsibility of dealers and that of makers. Such being the cases, it has become necessary to confirm details about exposure to highly humid air or wetting with water, which have happened during transportation, storage or use to become a cause of failure or deterioration, and has been desired to develop a method for simple and accurate detection of exposure to moisture or water.
In JP-A-5-265143 and JP-A-5-232535 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d), substances easily dissolving in water and compounds changing their colors or forms upon contact with water, such as compounds deprived of crystalline water, are disclosed as moisture detecting means. For instance, the substances easily dissolving in water include moisture testing paper made by Toyo Roshi Kaisha, Ltd., Oblate, low molecular weight polyvinyl alcohol and sodium polyacrylate, and the compounds deprived of crystalline water include anhydrous copper sulfate and anhydrous cobalt chloride. However, the use of such means has drawbacks of lacking convenience and being insufficient for clear determination. In addition, JP-A-9-325698 discloses the water-resistant sheet having a water-soluble film window for wet detect, and JP-A-10-2893 discloses the wet-sensing matter printed on a sheet having low water repellency with waterless lithographic printing ink containing a water-soluble dye. In the case of the former detect sheet, wetting is visually perceivable by dissolution of the water-soluble film. In the case of the latter sensing printed matter, on the other hand, wetting is visually perceivable by permeation of the water-soluble dye eluted from printed areas into non-printed areas. However, both cases still have problems with lucidity of standards for determination. Further, JP-A-2000-105230 discloses the wetness detecting method and label using a colorant composition comprising an electron-accepting color-development compound and an electron-donating coloration compound and thereby enabling disappearance of color upon contact with water. However, all the methods cited above hardly permit evaluation of an exposure story under high humidity conditions, which do not yet reach the condition of wetting with water.
A problem tackled by the invention is to provide a moisture/wetness detecting method which enables judgement as to whether or not easily portable precision equipment intended for use outdoors has undergone an improper usage condition, such as submersion in water or wetting with water, or whether or not articles of the type which are liable to suffer deterioration or have troubles when they are brought into contact with moisture or water have been in an inappropriate condition, specifically they have been placed under high humidity or have been gotten wet in rain, in the course of transportation or storage.
Another problem tackled by the invention is to provide a moisture/wetness detecting label enabling detection of a history of exposure to high humidity or wetting with water by being affixed to the outside or inside of an article which requires detecting whether or not it has undergone exposure to high humidity or wetting with water.
Still another problem tackled by the invention is to provide an article having convenient function for checking on a history of exposure to high humidity or a history of wetting with water by the use of the aforementioned moisture/wetness detecting method or label.
A further problem tackled by the invention is to provide a detecting material that permits easy detection of a history of contact with a liquid like water or a liquid vapor by a change in its color.
A still further problem tackled by the invention is to provide a detecting method that makes it possible to detect easily whether or not various articles have come into contact with a liquid like water or a liquid vapor during use, storage or transportation.
In order to solve the aforementioned problems, the present moisture/wetness detecting method comprises using a composite material which contains at least one water-soluble decoloring agent and at least one methine dye, the color of which disappears upon reaction with the decoloring agent, in a state that the decoloring agent and the dye are spatially isolated from each other, and detecting a history of contact with moisture or water by disappearance of color from the composite material. Further, the present moisture/wetness detecting label enabling solution of the aforementioned problems is characterized in that at least one water-soluble decoloring agent and at least one methine dye, the color of which disappears upon reaction with the decoloring agent, are coated on a support in a state that the decoloring agent and the dye are spatially isolated from each other. Furthermore, the foregoing problems are solved by articles with a moisture/wetness detecting function that are characterized by the provision of a moisture detect component comprising a support coated with at least one water-soluble decoloring agent and at least one methine dye, the color of which disappears upon reaction with the decoloring agent, in a state that the decoloring agent and the dye are spatially isolated from each other.
In addition, the present detecting material that can bring about a solution of the foregoing problems is characterized by comprising at least one decoloring agent and at least one colorant, the color of which disappears upon reaction with the decoloring agent, in a state that decoloring reaction is prevented from proceeding. Therein, the decoloring reaction between part or all of the colorant and the decoloring agent is caused upon contact with the liquid, the liquid vapor or both in which at least either the decoloring agent or the colorant is soluble to result in disappearance of the colorant""s color and enables the detection of contacts with the liquid, the liquid vapor or both.
In the present detecting material, the reaction between the colorant and the decoloring agent proceeds upon contact with the liquid, the liquid vapor or both. As a result, part or all of the colorant loses its color, and thereby the contact with liquid, liquid vapor or both is detected. Therefore, the contact of the present detecting material with a liquid, liquid vapor or both can be detected by visually perceivable color change, and evaluation of contact with a liquid, a liquid vapor or both can be made with ease.
In accordance with a preferred embodiment of the present invention, the detecting material comprises a detecting layer comprising at least one layer comprising a decoloring agent and a colorant in a state that the decoloring agent and the colorant are spatially isolated from each other, and at least a part of the detecting layer loses or changes its color upon contact with a liquid, a liquid vapor or both in which at least either the decoloring agent or the colorant is soluble.
In a preferred embodiment of the present detecting material, the detecting layer comprises a decoloring agent layer comprising the decoloring agent as defined above and a colorant layer comprising the colorant as defined above.
In a much preferable embodiment of the present detecting material, the decoloring agent and colorant layers comprise a binder capable of absorbing the liquid, the liquid vapor or both as defined above.
When the liquid is water, gelatin is preferred as the binder.
In a further preferred embodiment of the present detecting material, the material further comprises a member for leaving a space between the decoloring agent layer and the colorant layer in a state that the liquid, the liquid vapor or both is capable of permeating through the member.
In another preferable embodiment of the present detecting material, the material further comprises an interlayer that is sandwiched between the decoloring agent layer and the colorant layer and has channels leading to both the decoloring agent layer and the colorant layer.
Therein, it is preferable that the interlayer have a thickness of 0.1 to 100 xcexcm.
In still another preferable embodiment of the present detecting material, the material further comprises underneath or inside the detecting layer a display plane bearing characters, drawings or both, and thereby the characters, drawings or both can be visually recognized when a part or all of the detecting layer loses its color.
In the present detecting materials according to the foregoing embodiments, it is preferable that the colorant be a methine dye or an azomethine dye.
In order to solve the aforementioned problems, the present method for detecting at least one of a storage history, a use history and a transportation history of an article comprises fitting an article with a detecting material according to the invention, and checking after at least one of storage, use and transportation of the article whether or not the detecting material has lost its color.